Codec corrupted, now Green screen on Windows Media Center - help m

Windows Media Center worked great. Then I installed some codec packs - I
have now learned my lesson. I am running Vista 64. I have uninstalled the
codec packs yet I still have the green screen for live TV that shows a frame
of picture every few seconds, accompanied with a little haulted sound.

I have read other post suggesting that the Mpeg-2 decoder is the problem -
However, I have not found a way to address this on vista 64. I have also
reinstall TV card drivers, installed 3rd party Mpeg-2 decoders, and tried the
Vista MediaCentre utility.

What I really really want is a repair tool - that will reset all codec,
registries, whatever it takes to have it working as it was when I first
install vista.

Further, Windows Media Player works fine - and there are no codec glitches
there.